Method and equipment for track manufacture



July 11, 1950 HR. MILLER ETAL METHOD AND EQUIPMENT FOR TRACK MANUFACTURE 3 Sheets-Sheet 1 Filed Sept. 2a, 194

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METHOD AND EQUIPMENT FOR mcx MANUFACTURE Filed Sept. 23, 1948 eefs-Sheet 2 Herman/R/Vfl/er L. Y

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METHOD AND EQUIPMENT FOR TRACK MANUFACTURE mm VV 0M 7 w 3 2C: m 1 I mm. Q, m M

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Patented July 11, 1950 UNITED STATES PATENT OFFICE.

METHOD AND EQUIPMENT FOR TRACK MANUFACTURE Hamil, R. Miller and Ralph W. Sohl, Marshallville, Ohio, assignors to Wingfoot Corporation, Aln'on,- Ohio, a corporation of Delaware Application September 23, 1948, Serial No. 50,854 I 16 Claims.

- overcure at theends-of each section due to overlapping, or, buildthe'band .on a form, then strip and; place in a mold provided with an expanding sectional metal coreto apply pressure. while vulcanizingtheband.

Previous methods and equipment or apparatus used in the manufacture of band tracks of the present type required more floor space, the equip- I ment used was heavy, more costly and dilllcult to handle resulting ina greater cost of producing the bands than does the present method and equipment.

It is the general object of the present invention to avoid and overcome the foregoing difficulties and objections of prior practices by the provision of a more eflicient and less expensive method of producing flexible endless band tracks of the present type.

Another object is to provide a method and ap-- paratus that will eliminate heavy equipment or apparatus and the laborious task of handling and moving same with a reduction in time and labor which will be reflected in lower cost of the product.

Another object of the invention is to provide a method and apparatus in which band tracks are molded with wire reinforcement plies under tension so that there will be little or no stretch when in service on a vehicle.

The aforesaid objects of the invention, and other objects which will become more apparent as the description proceeds, may be achieved by providing a resilient-inflatable form of unusual dimensions which may be mounted on a split ring which, in turn, is mounted on a revolving chuck, partially inflating the form to give it stability. fabricating a band on the outer periphery of said, form, then placing the form with the ring and band thereon in a mold, fully inflating the. form, then subjecting the band to heat-and pressure while under tension to vulcanize same, after which the form is removed from said mold and deflated, whereupon the band is easily removed from said form.

For a'better understand n of. intimation:

(Cl. H)

2 reference should be had to the accompanying drawings wherein:

Figure '1 is a diagrammatic view showing the inflatable form mounted on a power driven chuck with a band fabricatedthereon; l

Figure 2 is an enlarged sectional viw. of the band and form, mounted on the split 3 Figure 3 is a sectional view of a m'oldin which the form with the bandthereonand'siupporting ring is positioned for vulcanlzing the-band: ,j

. Figure 4 is a sectional view new the mold and form may 'befform'ed' so'fthat the band tracks may be formedand' inside out, then reversed after'being removed from; the mold; f'i' Figure 5 is a side view showing the-finished band applied to wheels; *1 I Figure 6 is a sectional view taken on the line, 6-6'of Figure 5; l

a With reference to Figure -'1 or the drawingsfla' conventional stand I supports a shaft 2 which is, driven by a sprocket 3 and chain 4 connected to a source ofpower not shown. Supported on'the shaft 2, a chuck 5 of conventional designhas arms 6 capable of radial extension and retraction by. the operation of the handwheel 1 through the cooperation of a gear and pinions (not shown) in the body of said chuck.

Mounted on the arms 6 of the chuck 5 is a split ring 8 composed of a pair of mating halves bolted together by the bolts 9. The ring has retaining flanges 10 formed at the outer edges. The base is provided with a slight taper or 'flare on either side of the center line extending to the retaining flanges to aid in centering the inflatable form I l thereon and to assure a central position in the mold.

The inflatable form or airbag Il may be composed of rubber, synthetic rubber, fabric or the like, and is capable of expanding when inflated.

will be of a tougher and stiifer nature when vulcanlzed is applied to the outer periphery. This stliier composition will give accuracy in molding the guiding ribs of the band track. The form or airbag is placed in a mold and vulcanized to its final circular shape.

sponding ribs-and grooves in the band man provide guiding ribs to retain the tracks on the wheels of a vehicle. The side walls of the form are arcuate and more flexible than the peripheral portion to permit proper extension of the form when inflated in a mold during the process of vulcanizing the band. The base 16 of the form is somewhat thicker, rendering the base stiffer than the sidewalls to provide stability when mounting on the split ring 8, the base being tapered to correspond to the taper of the split ring for convenience in mounting and centering the form or airbag.

A band track is fabricated on the form or airbag in the following manner, the form M is mounted on a chuck as illustrated lit-Fig. I: and partially inflated to a predetermined degree; fabric which may be a single sheet or a plurality of strips I1 is placed over the face of the form and stitched or rolled into the grooves and over the ridges, the fabric being of a width to permit the sides to'overhang so that it willlater extend over the sides and a portion ofthe upper surface of the band. track. For certain bands it may be advantageous to omit the fabric 11.. Strips of unvulcanized rubber [8 are rolled into the grooves .toforrn the guiding: ribs of the track, a sheet of rubber I9 is placed over the strips and stitched down, a plurality of plies of. reinforcing elements comprising rubberized wire fabric =-is centrally. positioned oven-the rubber sheet [9, the rubberized .fabric 20 isprepared :in sheetsrcut so thatthe. wire strands are at an angle with respect-tto the-center lineofthe track, the-various plies being alternately applied so-that the strands of each ply cross the strands of each preceding plyas illnstratedin Fig. 1-. By applying the wire plies in this manner a slight amount of stretch of the band. track-is permitted in the mold when the airbag or form is inflated but the stretch; of the band is negligible after being.- cured by' vulcanization. A sheet. of rubber M- is placed: over the plies of wirefabric and the loose sides of the fabric 11 are. applied to the sides and a: portion of the rubber sheet 2|. A sheet ofrubber 22 is then applied over the sides and top of thethus formed band and stitched down to finish the fabrication of the band track.

The split ring 8 with the form H and band 7 track 23-. thereon isremoved from thechuck 5 and the assembly placed in a mold- 24' (see: Fig. 3). The. form-is inflated by admittin'g fluidiunder pressure through the. valve stem 25 :.vhereup'on heat. and. pressure is applied to the mold to cure the bandtraclc byvulcanization.

The midis-composedoftwo' mating halves 26 andv 21 in which a cavity 28 is formed; to correspond with and receive the inflatable form, said, cavity being provided. with-an oilset portion 29' to receive and mold the band tracks The off-- set portionhas-ridgesill and: depressions 31 irrits circumfenence. to form the tread on'groundi contacting side fthe tank track; The guidlng' ribs 32' and. grooves 33 of the track are moldedby the ridges l1 and grooves 14 of the inflatable form andformthe guiding ribs: on the wheel,- contacting side of the tracks.

The offset portion 29 of the mold may be provided with a greater diameter than. the outside diameter of the fabricated band. This will permit the band to expand and be under: tension when. the form is inflated in the mold.

Figure 4 of thedrawings illustrates: a modifiedmethod. of. fabricating and" molding :the bands wherein the-operations-of: assemblingz'the :vao-ious elements-are-reversed. accomplishedxby- 4 forming ridges 34 and depressions 35 which mold the tread or ground contacting side of the band track on the inflatable form II. The ridges 36 and depressions 31 which form the band guiding ribs on the wheel contacting side are formed in the mold. By this method the band tracks will be molded inside out, thmreversed' when removed fromthe 32.

In this method the elements used in fabricating the band tracks are the same as used in the foregoingdescribed method but the sequence of applidatioii of the various elements is substantially reversed. The fabric over the guiding ribs is necessarily applied strips.

the-foregoing illustrations and description; it'hasbeetf disclosed how a method and the equipment .emplqyedtherein may be utilized to manufacture endless band tracks with economy and precision, which willprovide tracks that will give long troublefree wear at less cost than heretofore anoomplisl1edt While certain representative embodiments and details havebeen shown for purpose of illus-- trating: the invention; it will 'be apparentto thoseskilled in the art that various changesand modifications. may be: made'thereirr without departing fromrther-spiri-t or scope-oifithe invention;-

I} The" method-10f makingflexible enaless band trecksmoxiiprising forming and moldirig 'a flexible inflatable romr liavmgawide fiat mite? periphcry mith ridges and depres'siorrs formed thereon to: forma -design on onesidezot the track,- mount:

the=1 ornr m'a-splitrmg, mounting: the ririg on a. chuck, partially inflating th' serrate-form to a; predetermined liegreeg forfiilirg stand therestrips and the exposed fabric over said plying a; plurality or pliesor reinforcing elements over -the rubber-sheet, applying a sheet of rubberover said reinforcing elementsapplying:- the extending; rabric to rtne sfd es mo -a pbrtion" o'fthetopof the band, applying a third sheet of rubber over the sides and top of said band -to"- complete the band track;- placing the entire as'se r'nbl y includm'gthe ring-..aiid formin a mold and subject? ing. theband 'track -to-heat and pressure to vulcanize the band tiack u n'de'r tens-ion createdby the in'fiat'alble foiinl 2. The method of manufacturing flexible endless bandtrajok's cdniprising the following steps forming a-ilexible-inflatableform; mounting said' form-on a ring;- fabricating the band track on said -fbrn'r,--placih'g thie' assembly in amold an'd subjecting the band track -to'= heat and pressure to VmwmZ SameWhfleunder tension.

3; 'I he nie'blio'd ofimainufactuiing e'ndless'biand traclisfor traetbrs-comprisingthe'following steps, preparing --a flexible inflatable form, mounting said mrmaona an'omitting-rings mounting the rings on: a chuck, fabricating the band track on said fbnngrenio'vi'iig the assembly fioni' said chuckj placing tlie assembl'yirr a: mold and sub jectiiig the' band} tracle to= heat and" pressure same while under" tension.

4; 'r'he metliod of nranufacturihg endlessba'nd tracks rorfiaefiersoomprismgthe following steps, fomrinE-a=-flefil1lfiflaifiable 'fijrfil, mounting said formon a pair of mating rings; mounting" the rings on a chuck, fabricating theiiand t'ra'clg' on 'w sau mnatubieiorm removfiiguie assembly from zp eauoa said chuck, placing the assembly in a mold, inflating said inflatable form, and subjecting the band track to heat and pressure to vulcanize same while mounted on said inflatable form.

5. The method of making endless band tracks for tractors comprising forming an inflatable form having a substantially flat periphery and a wide base, mounting the inflatable form on a ring, mounting said ring on a chuck, inflating said inflatable form to a predetermined degree, fabricating a band track on the outer flat periphery of said form, placing the above recited assembly in a mold and subjecting said band track to heat and pressure to vulcanize said band track while under tension.

6. The method of making endless band tracks comprising forming an inflatable form having a wide flat outer face, mounting the form on a split ring, mounting the ring on a chuck, partially inflating said form, forming an endless band on the wide face of said form, placing the assembly in a mold, inflating said form to the proper molding pressure and subjecting said band to heat and pressure to vulcanize the same under tension.

7. The method of forming'and molding endless bands composed of rubber and fabric having strands of reinforcing material embedded therein, comprising forming an inflatable flexible form, mounting the form on a pair of mating rings, said rings being bolted together, partially inflating the flexible form, forming the endless band on the outer periphery of said inflatable flexible form, placing the thus formed band and form in a mold, further inflating said form to subject the band to pressure and heating said band to vulcanize the same while under tension due to the expansion of said inflatable form.

8. The method of producing flexible endless bands, comprising forming a resilient inflatable form, mounting the form on a pair of mating rings, mounting said rings on a chuck, partially inflating said inflatable form, forming the endless band on the outer periphery of the inflatable form, placing the assembly in a mold, inflating the resilient form to molding pressure, and applying heat and pressure to said band to vulcanize the same while under tension created by the resilient inflatable form.

9. The method of forming and molding flexible endless band tracks comprising forming a resilient inflatable form, mounting said form on a pair of mating rings, mounting said rings on a chuck, partially inflating the inflatable form, forming the band track on the outer periphery of said form, enclosing the assembly in a mold, inflating the form to molding pressure, subjecting the band track to heat and pressure to vulcanize the same, deflating said form, removing the assembly from the mold and stripping the band track from the resilient inflatable form.

10. The method of curing endless band tracks comprising the steps of forming a band on the exterior of an inflated form and, while still mounted on said form, enclosing the band and form in a mold and curing said band.

11. An apparatus for forming and vulcanizing flexible band tracks, comprising an inflatable building form on which the band track is fabricated, a mold having a cavity therein in which said band track is vulcanized while on said inflatable form and a pair of mating rings for supporting said inflatable form outside the mold while the band track is being formed and for supporting same inside the mold while the band track is being vulcanized.

12. An apparatus for forming and vulcanizing flexible band tracks, comprising an inflatable building form on which the band track is fabricated, a mold having a cavity therein in which said band track is vulcanized while on said inflatable form, a pair of mating rings for supporting said inflatable form outside the mold while the band track is being formed and inside the mold while the band track is being vulcanized, and ridges on said mold extending into said mold cavity to form a design on one side of the band track and ridges extending from said inflatable form to form a design on the opposite side of said band.

13. An apparatus for forming and vulcanizing flexible band tracks, comprising an inflatable building form on which the band track is fabricated, a mold having a cavity therein in which said band track is vulcanized while on said in-- flatable form, a pair of mating rings for supporting said inflatable form outside the mold while the band track .is being formed and inside the mold while the .band track is being vulcanized, and ridges extending from said inflatable form to form guiding ribs on said band track.

14. An apparatus for forming and vulcanizing flexible 'band tracks, comprising an inflatable building formon which a band is fabricated, a mold having a cavity therein in which said band is vulcanized while on said inflatable form, a ring for supporting said inflatable form outside the mold while the band is being formed and inside the mold while the band is being vulcanized and ridges extending from said inflatable form to form a design on the adjacent side thereto.

15. Equipment for forming and vulcanizing flexible band track comprising a flexible inflatable .form on which a band is fabricated, a mold having a cavity therein, a ring to support said inflatable form while it is both outside and inside of said mold, said inflatable form having a wide flat outer periphery with ridges and depressions formed therein to form a design in the band track, arcuate sidewalls, and having cross sectional dimensions such that the width is greater than the height.

16. The method of curing endless flexible bands comprising the steps of forming a band on the outer periphery of a flexible form and while still mounted on said form enclosing the band and form in a mold inflating said form and curing said band thereon.

HERMAN R. MILLER. RALPH W. SOHL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,510,449 Brucker Sept. 30, 1924 1,633,587 Kilborn et al June 28, 1927 2,363,933 Bendix Nov. 28, 1944 

